Energy storage element

ABSTRACT

An energy storage element includes a container that includes a container body including an opening and a cap part formed on the opening, an electrode assembly housed in the container, an electrode terminal, and a current collector which electrically connects the electrode terminal and the electrode assembly. The cap part of the container includes an outer surface including a protrusion part formed to protrude outward from the outer surface, and an inner surface including a recess part formed at a position corresponding to a position of the protrusion part.

This application as a Continuation application of U.S. patentapplication Ser. No. 13/688,079, filed on Nov. 28, 2012, the disclosureof which is incorporated herein in its entirety by reference.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is based on and claims priority of JapanesePatent Application No. 2011-261069 filed on Nov. 29, 2011 and JapanesePatent Application No, 2012-247745 filed on Nov. 9, 2012. The entiredisclosures of the above-Identified applications, including thespecifications, drawings and claims are incorporated herein by referencein their entirety.

FIELD

The present invention relates to an energy ‘storage element such as asecondary battery and another battery.

BACKGROUND

Secondary batteries are used as replacements for primary batteries, andhave been wide spread as power sources for electric appliances such asmobile phones and information technology (IT) devices. In particular,non-aqueous electrolyte secondary batteries represented by lithium ionbatteries have high energy density and are increasingly applied to largeindustrial electric apparatuses such as electric vehicles.

A conventional non-aqueous electrolyte secondary battery has connectionparts each of which is for connecting (i) a corresponding one of currentcollectors disposed inside the container of the battery and iselectrically connected to a corresponding one of a positive electrodeand a negative electrode in the electrode assembly disposed inside thecontainer and (ii) a corresponding one of the electrode terminalsoutside the container, so that electric energy generated by theelectrode assembly can be extracted. Each of the connection parts isformed integrally with the corresponding electrode terminal to penetratethrough the cap part of the container, so as to connect thecorresponding current collector inside the container and the electrodeterminal outside the container. For this reason, the cap part hasthrough-holes for allowing penetration of the respectively correspondingconnection parts.

The container is generally made of metal, and thus there is a need toinsulate the container areas in which through-holes are formed and theelectrode terminals, the connection parts, and the current collectors.This is because a short circuit is caused in the container if theconnection parts penetrate through the cap part of the container via thethrough-holes without any insulation. In addition, the containercontains electrolyte together with the electrode assembly, and there isa need to prevent the electrolyte from leaking to the outside of thecontainer through the through-holes.

In order to insulate the container and the electrode terminals, theconnection parts, and the current collectors, and prevent theelectrolyte from leaking to the outside of the container through thethrough-holes, a conventional energy storage element includes insulationsealing members provided to cover the cap part areas in which thethrough-holes of the container are formed at the outside and inside ofthe cap part of the container. For example, both the insulation andsealing between the container and the electrode terminals, theconnection parts, and the current collectors are achieved by means ofthe connection parts pressure-bonding the electrode terminals outsidethe container and the current collectors inside the container in a statewhere the container areas having the through-holes are covered at boththe inside and outside of the cap part of the container by theinsulation sealing members (see Patent Literature below).

CITATION LIST Patent Literature

[PTL 1]

Japanese Unexamined Patent Application Publication No. 2010-097822

SUMMARY

The present invention has been made in view of the aforementionedproblems, with an aim to provide an energy storage element which can beeasily made with a large tolerance and at a low cost.

In order to achieve the aforementioned aim, an energy storage elementaccording to an aspect of the present invention is an energy storageelement which includes: a container; an electrode assembly housed in thecontainer; an electrode terminal; a current collector which electricallyconnects the electrode terminal and the electrode assembly; and aninternal insulation sealing member which insulates the container and thecurrent collector, wherein the container includes a wall having an outersurface and an inner surface, the outer surface has a protrusion partformed to protrude outward from the outer surface, the inner surface hasa recess part formed at a position corresponding to a position of theprotrusion part, the recess part has a bottom surface which is outermostand an inner side surface formed continuously between the bottom surfaceand the inner surface of the wall of the container, at least part of theinner side surface of the recess part is formed to be tilted withrespect to a direction in which the protrusion part protrudes, and theinternal insulation member is positioned between the current collectorand the recess part of the container, and has a first wall part which isparallel to the at least part of the inner side surface of the recesspart.

As described above, the at least part of the inner side surface of therecess part formed on the inner surface of the wall part of thecontainer and the first side wall part facing the at least part of theinner side surface of the recess part of the internal insulation memberare formed to be parallel to each other and be tilted with respect tothe protrusion direction of the protrusion part. In this way, forexample, when the portions of the inner side surface of the recess partare tilted so as to be farther apart from each other at positions moredistant from the bottom surface, it is possible to easily bring the atleast portions of the inner side surface of the recess part and thefirst side wall part of the internal insulation member into closecontact with each other even if the recess part or the internalinsulation member are formed with some tolerance, and to thus increasethe air-tightness around the electrode terminal.

In addition, the at least part of the inner side surface of the recesspart may be in surface contact with the first wall part of the internalinsulation member, the first wall part being parallel to the at leastpart of the inner side surface.

In addition, the at least part of the inner side surface of the recesspart may be paired portions facing each other in the inner side surface,and the paired portions may be tilted so as to be farther apart fromeach other at positions more distant from the bottom surface.

For this reason, it is possible to bring the recess part which is formedon the inner surface of the wall of the container and the internalinsulation member into close contact with each other, and to therebyincrease the air-tightness around the electrode terminal.

In addition, the paired portions facing each other in the inner sidesurface of the recess part may be tilted symmetrically with respect to adirection in which the protrusion part protrudes.

With the symmetrical configuration, it is possible to easily match therecess part and the internal insulation member even if one of theorientation of the recess part and the orientation of the Internalinsulation member changes by 180 degrees with respect to the other. Inother words, it is possible to easily align the recess part and theinternal insulation member.

In addition, the internal insulation member may further include a platepart provided along a bottom surface of the recess part, the first wallpart may be paired first wall parts formed continuously from the platepart, and may be parallel to the paired portions facing each other inthe inner side surface of the recess part, and the paired first wallparts may be tilted so as to be farther apart from each other atpositions more distant from the plate part.

In addition, the inner surface of the wall of the container may berectangular, and the paired portions facing each other in the inner sidesurface of the recess part may be formed along a longitudinal directionof the inner surface of the wall of the container.

In addition, the current collector may be connected to the electrodeterminal, in the recess part.

In this way, the current collector is electrically connected to theelectrode terminal in the recess part of the container. In addition, thecontainer includes a protrusion part, and the recess part is formed atthe position corresponding to the position of the protrusion part.

In this way, the part of the current collector connected to theelectrode terminal is housed in the recess part formed on the innersurface of the cap part of the container. Thus, it is possible to matchthe space for parts other than the recess part in the inner space of thecontainer to the shape of the electrode assembly. In this way, it ispossible to reduce wasteful space produced when the electrode assemblyis housed inside the container only by adjusting the outer size of theelectrode assembly to the size of the inner space. In this way, theshape of the container is adjusted to the shape of the electrodeassembly without changing the structure of the electrode assembly.Therefore, it is possible to easily increase the housing efficiency ofthe electrode assembly with respect to the inner space of the container.In this way, it is possible to increase the energy storage capacity perunit volume of the energy storage element.

In addition, the current collector may include a base part which isconnected to the electrode terminal, in the recess part, and theinternal insulation member may insulate the container and the currentcollector by being sandwitched by the recess part of the container andthe base part.

In this way, the current collector is connected to the electrodeterminal at a position inside the recess part of the container, and theinternal insulation member is housed at the position at which thecurrent collector is in contact with the recess part. In addition, forexample, when the first side wall part of the internal insulation memberto be in contact with the current collector is formed to have partstilted so as to be farther apart from each other at positions moredistant from the plate part, it is possible to form the base part of thecurrent collector to have a shape matching the shape of the first sidewall part of the internal insulation member. In addition, in this case,and when the current collector includes paired arm parts forsandwitching the electrode assembly, it is possible to easily secure awide spacing between the paired arm parts for sandwitching the electrodeassembly. In this way, it is possible to increase the size of theelectrode assembly to be sandwitched by the paired arm parts. In otherwords, it is possible to increase the volume of the electrode assemblyto be housed inside the container, and thereby further increase thehousing efficiency of the electrode assembly with respect to thecapacity of the container. In this way, it is possible to increase theenergy storage capacity per unit volume of the energy storage element.

In addition, the current collector may further include an arm part whichextends from the base part toward a side opposite to the direction inwhich the protrusion part protrudes, and which is connected to theelectrode assembly, and the arm part may include an arm body which isconnected to the electrode assembly and a bridge part which connects thearm body and the base part.

In addition, the base part may include: a plate part which is directlyconnected to the electrode terminal; and a wall part which is formedcontinuously from the bridge part and is bent or curved with respect tothe plate part, and the wall part of the base part may face the innerside surface of the recess part through the first wall part of the innerinsulation member.

In addition, the wall part of the base part may be in surface contactwith the first wall part of the internal insulation member.

Furthermore, the energy storage element according to an aspect of thepresent invention may be an energy storage element which includes: acontainer; an electrode assembly housed in the container; an electrodeterminal; a current collector which electrically connects the electrodeterminal and the electrode assembly; and an external insulation sealingmember which insulates the container and the electrode terminal, whereinthe container includes a wall having an outer surface and an innersurface, the outer surface has a protrusion part formed to protrudeoutward from the outer surface, the protrusion part has a top part whichis outermost and an outer side surface formed continuously between thetop part and the outer side surface of the wall of the container, atleast part of the outer side surface is provided to be tilted withrespect to a direction in which the protrusion part protrudes, and theexternal insulation member is disposed between the electrode terminaland the protrusion part of the container, and includes a second wallpart parallel to the at least part of the outer surface of theprotrusion part.

In addition, the container may further include a recess part formed at aposition corresponding to a position of the protrusion part, and thecurrent collector is connected to the electrode terminal, in the recesspart.

As described above, the at least part of the outer side surface of theprotrusion part on the outer surface of the container and the secondside wall part facing the at least part of the outer side surface of theprotrusion part of the external insulation member are formed to beparallel to each other and be tilted with respect to the protrusiondirection of the protrusion part. In this way, for example, when theportions of the outer side surface of the protrusion part are tilted soas to be farther apart from each other at positions more distant fromthe top part of the protrusion part, it is possible to bring the atleast portions of the outer side surface of the protrusion part and thesecond side wall part of the external insulation member into closecontact with each other even if the protrusion part and the externalinsulation member are formed with some tolerance, and to thus increasethe air-tightness around the electrode terminal.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the invention willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present invention.

FIG. 1 is a schematic exploded perspective view of a non-aqueouselectrolyte secondary battery according to an embodiment of the presentinvention.

FIG. 2 is a cross-sectional view, in the Y-Z plane, of main parts aroundone of the electrode terminals of the non-aqueous electrolyte secondarybattery.

FIG. 3 is a cross-sectional view, in the X-Z plane, of main parts aroundthe electrode terminals of the non-aqueous electrolyte secondarybattery.

FIG. 4 is a perspective view of one of the current collectors of thenon-aqueous electrolyte secondary battery.

FIG. 5A is a view of a current collector when viewed in the Y-axisdirection in a non-aqueous electrolyte secondary battery according tothe present invention.

FIG. 5B is a view of the collector when viewed in the X-axis directionin the non-aqueous electrolyte secondary battery.

FIG. 6 is a partial plan view schematically showing components around acap part of the non-aqueous electrolyte secondary battery.

FIG. 7 is a view of one of exemplary current collectors when viewed inthe Y-axis direction in a non-aqueous electrolyte secondary batteryaccording to the present invention.

FIG. 8 is a cross-sectional view of components around one of theelectrode terminals of a non-aqueous electrolyte secondary batteryhaving another structure according to the present invention.

FIG. 9 is a schematic exploded perspective view of a non-aqueouselectrolyte secondary battery according to a conventional technique.

FIG. 10 is a cross-sectional view of the non-aqueous electrolytesecondary battery according to the conventional technique.

DESCRIPTION OF EMBODIMENTS

When manufacturing a conventional energy storage element, the followingproblem arises that it is difficult to provide components such aselectrode terminals while maintaining designed postures thereofespecially when the electrode terminals do not have the shape of acircle having a center axis that matches the center axis of thethrough-holes because insulation sealing members rotate about the centeraxis of the through-holes when the electrode terminals and currentcollectors are pressure-bonded by connection parts.

In order to solve this problem, as shown in FIG. 9 and FIG. 10, theabove-identified Patent Literature 1 further provides: (i) around athrough-hole 120 c, a protrusion part 120 b which protrudes outward froma container 300 and has a non-circular shape in a top view; and (ii) aninsulation sealing member 121 with a rotation preventing part 121 bwhich is a side surface of the protrusion part 120 b. In other words,the rotation preventing part 121 b provided to the insulation sealingmember 121 is engaged with the side surface of the protrusion part 120 bformed in the container 300, which prevents the Insulation sealingmember 121 from rotating about the through-hole 120 c. FIG. 9 is aschematic exploded perspective view of a conventional non-aqueouselectrolyte secondary battery. FIG. 10 is a cross-sectional view of mainparts around the electrode terminals of the conventional non-aqueouselectrolyte secondary battery.

However, as shown in FIG. 10, the non-aqueous electrolyte secondarybattery 100 includes a cap part 120 having an upper surface 120 a, awall surface 120 d formed to stand on the upper surface 120 a, and aprotrusion part 120 b formed partly integrally with the wall surface 120d. In this way, the electrode terminal 130 and the current collector 112are connected to each other in the non-aqueous electrolyte secondarybattery 100 having the protrusion part 120 b, and thus, a space S1 isinevitably produced between the recess part 120 e and the internalinsulation sealing member 113. For this reason, when the container 300,the external insulation sealing member 121, the internal insulationsealing member 113, and the current collector 112 are pressure-bonded bya riveted end of the electrode terminal 130, the container 300, theexternal insulation sealing member 121, the internal insulation sealingmember 113, and the current collector 112 are inevitably deformed towardthe inside of the space S1. For this reason, it is difficult to secureair-tightness of the container 300.

In view of this, examples of conceivable solutions to such problemsinclude to form an internal insulation sealing member and a currentcollector each having a shape matching the shape of the space S1 insidethe recess part 120 e. In other words, it is conceivable to employ aconfiguration for securing air-tightness in which a wall part parallelto the wall surface 120 d of the protrusion part 120 b is formed as theinternal insulation sealing member (not shown), and the internalinsulation sealing member is interfit with the inside of the recess part120 e such that the wall part of the internal insulation sealing memberand the wall surface 120 d of the recess part 120 e abut each other.With this, it is possible to secure air-tightness of the container 300because there is no such space S1 in the recess part 120 e.

However, when such a configuration is realized, both the recess part andthe internal insulation sealing member 113 need to be precisely formed.In other words, when the internal insulation sealing member 113 islarger than the recess part, the internal insulation sealing member 113cannot naturally be interfit with the recess part. On the other hand,when the recess part is larger than the internal insulation sealingmember 113, the internal insulation sealing member 113 turns or rotatesabout an axis that is the connection part 131 at a small angle in therecess part (in other words, the internal insulation sealing member 113displaces). This is a factor that affects the air-tightness around theelectrode terminal 130.

In this way, in order to secure air-tightness around the electrodeterminal 130, each of the recess part of the cap part 120 and theinternal insulation sealing member 113 needs to be formed to have ahighly precise size. However, this lengthens the manufacturing processesand increases the manufacturing cost.

Hereinafter, an embodiment of the present invention is described withreference to the drawings. The exemplary embodiment described belowshows a specific preferable example. The numerical values, shapes,materials, structural elements, the arrangement and connection of thestructural elements etc. shown in the following exemplary embodiment aremere examples, and therefore do not limit the scope of the presentinvention. Therefore, among the structural elements in the followingexemplary embodiment, structural elements not recited in any one of theindependent claims defining the most generic concept of the presentinvention are described as arbitrary structural elements in preferableimplementations.

EMBODIMENT

FIG. 1 is a schematic exploded perspective view of a non-aqueouselectrolyte secondary battery 1 having an exemplary structure accordingto an embodiment of the present invention.

As shown in FIG. 1, the non-aqueous electrolyte secondary battery 1according to this embodiment includes: a container 30; an electrodeassembly 11 housed inside the container 30; an electrode terminal 23;current collectors 12 and 15 for electrically connecting the electrodeterminal 23 and the electrode assembly 11; an external insulationsealing member 22 which insulates the container 30 and the electrodeterminal 23; and an internal Insulation sealing member 13 for insulatingthe container 30 and the current collectors 12 and 15.

The container 30 includes a container body 10 and a cap part 20. The cappart 20 is a member having a long plate shape extending in the X-axisdirection (described later), and forms a part of the inner wall of thecontainer 30. The container body 10 is a rectangular cylindrical memberhaving an opening 10 x at a first end and a bottom at a second end. Inthis embodiment, the direction in which the container body 10 and thecap part 20 are arranged is referred to as an upper-lower direction (theZ-axis direction in FIG. 1), the direction in which a positive terminaland a negative terminal are arranged is referred to as a left-rightdirection (the Y-axis direction in FIG. 1), and the directionperpendicular to the upper-lower direction and the left-right directionis referred to as a front-back direction (the X-axis direction in FIG.1).

The cap part 20 includes, at each of the end parts in the lengthwisedirection, a protrusion part 21 which protrudes outward from an uppersurface 20 b of the cap part 20 of the container 30 and a plate-shapedcap body 20 a which is the part other than the protrusion part 21. Here,the upper surface 20 b of the cap part 20 is an outer surface of the capbody 20 a of the container 30. In other words, the cap part 20 of thecontainer 30 includes a wall having an outer surface partly protrudesoutward to be the protrusion part 21.

The protrusion part 21 includes a plate part 21 b which is a top partand a side wall part 21 d. The plate part 21 b is a flat-plate shapedmember which makes up the upper part of the protrusion part 21, has ashape of a rectangle having parallel sides in the X-axis direction andthe Y-axis direction in a plan view, and is parallel to the cap body 20a. In addition, the protrusion part 21 includes the plate part 21 b witha through-hole 21 a for allowing penetration of the electrode terminal23. Here, FIG. 1 shows only a through-hole 21 a at the positiveelectrode side, and does not show a-through-hole at the negativeelectrode side because the latter through-hole is hidden behind aninsulation sealing member later described.

An electrode assembly 11 is formed by stacking band-shaped positive andnegative electrodes with a separator inbetween and winding the wholestack in the shape of a long cylinder. The electrode assembly 11 ishoused in the container 30 in the direction in which the winding axisdirection matches the Y-axis direction and the long axis of the crosssection which is a long circle in shape matches the Z-axis direction.The positive electrode and the negative electrode are shifted from eachother in the winding axis direction and are wound about the winding axisdirection in the shape of the long circle. The electrode assembly 11includes projection parts 11 a and 11 b corresponding to the positiveelectrode and the negative electrode and each of which projects outwardfrom a corresponding separator in the winding axis direction (the Y-axisdirection) of the electrode assembly 11. In other words, the electrodeassembly 11 includes the projection part 11 a disposed at the positiveelectrode side and projecting from the separator at a first end in thewinding axis direction, and the projection part 11 b disposed at thenegative electrode side and projecting from the separator at a secondend in the winding axis direction. Furthermore, the projection part 11 aat the positive electrode side and the projection part 11 b at thenegative electrode side do not include any active material, and thusmetal foil which is a base material thereof is exposed. Morespecifically, the projection part 11 a at the positive electrode sideincludes exposed aluminum foil which is the base material of thepositive electrode without any positive electrode active layer, and theprojection part 11 b at the negative electrode side includes exposedcupper foil which is the base material of the negative electrode withoutany negative electrode active layer. To the projection part 11 a at thepositive electrode side and the projection part 11 b at the negativeelectrode side, a current collector 12 at the positive electrode sideand a current collector 15 at the negative electrode side areelectrically connected, respectively.

The current collector 12 has an upper end part with a plate-shaped part(a plate part 12 b 1 later described) which is parallel to the uppersurface of the electrode assembly 11 (which is parallel to the X-Yplane). The plate-shaped part has a through-hole 12 a. The currentcollector 12 disposed at the positive electrode side which is a firstend of the winding axis direction in which the electrode assembly 11 iswound has curved sides (arm parts 12 c described later) which are alongan outer side surface in the X-axis direction of the projection part 11a and which extend in the Z-axis direction. These curved sides aresandwitched by holding plates 14 made of aluminum or an aluminum alloytogether with the projection part 11 a at the positive electrode side,and are connected and fixed by ultrasonic welding or the like. Thecurrent collector 15 at the negative electrode side also has the same orsimilar structure, and is formed with cupper or a cupper alloy. Thecurrent collector 12 at the positive electrode side and the currentcollector 15 at the negative electrode side are the same or similar instructure. Thus, only the current collector 12 at the positive electrodeside is described, and the current collector 15 at the negativeelectrode side is not described.

The structure of the current collector 12 (and the current collector 15)is described in detail later.

The Internal Insulation sealing member 13 is an insulation member whichInsulates the container 30 and the current collector 12 by beingsandwitched between the recess part 21 x (see a later-provideddescription) of the cap part 20 and the base part 12 b (see alater-provided description) of the current collector 12. In other words,the internal insulation sealing member 13 is an insulation member whichis disposed inside the container 30 and is for insulating the container30 from the electrode assembly 11 electrically connected via the currentcollector 12. In addition, the internal insulation sealing member 13functions as a sealing member (packing) for sealing the through-hole 21a by being pressure-bonded to the through-hole 21 a formed in the cappart 20 of the container 30 together with the electrode terminal 23 andthe external insulation sealing member 22. The internal insulationsealing member 13 has a shape for covering the base part 12 b of thecurrent collector 12 from the side of the electrode terminal 23. TheInternal Insulation sealing member 13 is made of a synthetic resin orthe like, and has insulation and elastic properties. In addition to thethrough-hole 21 a of the cap part 20 and the through-hole 12 a of thecurrent collector 12, the internal insulation sealing member 13 includesa through-hole 13 a for allowing penetration of a connection part 23 b(later described) of the electrode terminal 23.

The external insulation sealing member 22 is an insulation member whichinsulates the electrode terminal 23 and the container 30 by beingsandwitched between the terminal body 23 a (later described) of theelectrode terminal 23 and the protrusion part 21 of the cap part 20. Inother words, the external insulation sealing member 22 is an insulationmember which is disposed outside the container 30 and is for insulatingthe container 30 from the electrode assembly 11 electrically connectedvia the electrode terminal 23 and the current collector 12. In addition,the external insulation sealing member 22 functions as a sealing member(packing) for sealing the through-hole 21 a by being pressure-bonded tothe through-hole 21 a formed in the cap part 20 of the container 30together with the electrode terminal 23 and the internal insulationsealing member 13. The external insulation sealing member 22 is disposedon the plate part 21 b of the protrusion part 21, and includes acylinder-shaped cylinder part 22 c which is formed to be in contact witha through-hole 22 d in the plate part 22 b and to extend below the platepart 22 b. In other words, the external insulation sealing member 22includes the cylinder part 22 c and the plate part 22 b extending in thedirection which is a direction crossing the axis of the cylinder part 22c and outward of the cylinder part 22 c.

In addition, the external insulation sealing member 22 includes a sidewall part 22 a as a second wall part formed at the outer edge of theplate part 22 b along the side surface of the protrusion part 21. Inother words, the external insulation sealing member 22 is a memberincluding the plate part 22 b and the side wall part 22 a for coveringthe outside of the protrusion part 21.

The external insulation sealing member 22 is a member made of asynthetic resin, as in the case of the internal insulation sealingmember 13. The through-hole 22 d formed in the external insulationsealing member 22 allows penetration of the later-described electrodeterminal 23 by means of the connection part 23 b, in addition to thethrough-hole 21 a formed in the cap part 20, the through-hole 13 aformed in the internal insulation sealing member 13, and thethrough-hole 12 a formed in the current collector 12.

In addition, the cylinder part 22 c of the external insulation sealingmember 22 is formed at the side (the lower side of the plate part 22 b)facing the cap part 20, and has an inner edge which matches thethrough-hole 22 d. In addition, the cylinder part 22 c has an outer edgewhich fits into the through-holes 13 a and 21 a. Accordingly, thecylinder part 22 c is sandwitched between the through-hole 21 a formedin the protrusion part 21 of the container 30 and the connection part 23b of the electrode terminal 23. In other words, the external insulationsealing member 22 insulates the electrode terminal 23 and the container30 by being sandwitched between the terminal body 23 a of the electrodeterminal 23 and the plate part 21 b of the protrusion part 21 of thecontainer 30 and being sandwitched between the connection part 23 b ofthe electrode terminal 23 and the protrusion part area having thethrough-hole 21 a in the cap part 20 of the container 30.

Furthermore, a frame body 22 e is formed on the marginal area of theplate part 22 b which is of the external insulation sealing member 22and in which the through-hole 22 d is formed.

The electrode terminal 23 includes a plate-shaped terminal body 23 adisposed outside the protrusion direction of the protrusion part 21 onthe cap part 20 of the container 30 and a column-shaped connection part23 b which penetrates the through-hole 21 a formed in the recess part 21x. The terminal body 23 a has a flat outer edge corresponding to theshape of the inner edge of the frame body 22 e. The connection part 23 btakes roles for electrically connecting the terminal body 23 a and thecurrent collector 12 and mechanically bonding the cap part 20 and theelectrode assembly 11. The electrode terminal 23 disposed at thepositive electrode side is made of aluminum or an aluminum alloy, andthe electrode terminal disposed at the negative electrode side is madeof cupper or a cupper alloy.

The electrode terminal 23 is a member for completing electricalconnection between the non-aqueous electrolyte secondary battery 1 andan external load by means of the terminal being fixed by welding ontothe surface of the terminal body 23 a (the terminal is of the not-shownexternal load that is, a device which consumes electric energy of thenon-aqueous electrolyte secondary battery 1). Otherwise, the electrodeterminal 23 is a member for completing electrical connection between aplurality of non-aqueous electrolyte secondary batteries 1 (not-shown)arranged next to each other by means of the terminal bodies 23 a of therespective non-aqueous electrolyte secondary batteries 1 being fixed bywelding using a bus bar.

Here, the electrode terminal 23 may be configured such that the terminalbody 23 a and the connection part 23 b thereof are made of the samematerial by forging, casting, or the like. In addition, the electrodeterminal 23 may be configured such that the terminal body 23 a and theconnection part 23 b thereof are independent of each other, and that theterminal body 23 a and the connection part 23 b are integrally formedusing two different kinds of materials or the same material.

Next, with reference to FIG. 2 and FIG. 3, a detailed description isgiven of the structure of main parts around the electrode terminal 23and the current collector 12 of the non-aqueous electrolyte secondarybattery 1 according to this embodiment. FIG. 2 is a cross-sectionalview, in the Y-Z plane, of main parts around one of the electrodeterminals of the non-aqueous electrolyte secondary battery 1 alreadyassembled as shown in FIG. 1. FIG. 3 is a cross-sectional view, in theX-Z plane, of the main parts around the electrode terminal of thenon-aqueous electrolyte secondary battery 1 shown in FIG. 1.

As shown in FIG. 2 and FIG. 3, the structure of the main parts aroundthe electrode terminal 23 and the current collector 12 of thenon-aqueous electrolyte secondary battery 1 is a stack of the electrodeterminal 23, the external insulation sealing member 22, the protrusionpart 21 of the cap part 20, the internal insulation sealing member 13,and the plate part 12 b 1 of the current collector 12 stacked from abovein the listed order. The external insulation sealing member 22 isdisposed such that the plate part 22 b is stacked on a plate part 21 bof the protrusion part 21 on a plate part 13 b (see a later-provideddescription) of the internal insulation sealing member 13, and that thecylinder part 22 c penetrates through the through-hole 21 a formed inthe cap part 20 and the through-hole 13 a formed in the internalinsulation sealing member 13. The cylinder part 22 c has an end surfacewhich is on the same plane on which the lower surface of the internalinsulation sealing member 13 is present and, together with the lowersurface of the internal insulation sealing member 13, is above the uppersurface of the plate part 12 b 1 which forms the principal surface ofthe current collector 12. The inner circumference of the cylinder part22 c of the external insulation sealing member 22 and the through-hole12 a of the current collector 12 are approximately the same in size andshape. The cylinder part 22 c and the through-hole 12 a are penetratedby the connection part 23 b of the electrode terminal 23. In otherwords, the outer circumference of the connection part 23 b is in contactwith the inner circumference of the cylinder part 22 c and thethrough-hole 12 a in the current collector 12. The connection part 23 bof the electrode terminal 23 has a riveted end 23 c formed in the statewhere the connection part 23 b already penetrates through the cylinderpart 22 c of the external insulation sealing member 22 and thethrough-hole 12 a formed in the current collector 12. In other words,the electrode terminal 23 having the riveted end 23 c as apressure-bonding end part for sandwitching and pressure-bonding, in therecess part 21 x, the cap part 20 of the container 30 and the currentcollector 12 etc. together with the terminal body 23 a, and is therebyelectrically connected to the current collector 12.

Since the outer diameter of the riveted end 23 c is larger than thediameters of the respective through-holes 21 a, 22 d, 13 a, and 12 a,the external insulation sealing member 22, the cap part 20, the internalinsulation sealing member 13, and the current collector 12 arepressure-bonded to each other and integrally fixed by being sandwitchedby the terminal body 23 a of the electrode terminal 23 and the rivetedend 23 c. In this way, the electrode terminal 23 pressure-bonds theprotrusion part 21 of the container 30 and the external insulationsealing member 22, and thereby seals the protrusion part area having thethrough-hole 21 a in the cap part 20 of the container 30 and theelectrode terminal 23, using the external insulation sealing member 22and the internal insulation sealing member 13. In addition, since theelectrode terminal 23 is in contact with the current collector 12 at theconnection part 23 b and the riveted end 23 c, the electrode terminal 23is electrically connected to the current collector 12 in a state wherethe electrode terminal 23 already penetrates through the protrusion part21 of the cap part 20 via the through-hole. Here, since the side surfaceof the connection part 23 b is covered by the cylinder part 22 c of theexternal insulation sealing member 22, the cap part 20 and theconnection part 23 b are securely in an Insulated state.

Next, the structures of the respective parts are described.

As shown in FIG. 2 and FIG. 3, the cap part 20 in this embodiment isformed to have, on the back side (the lower side), a frame part 20 chaving an outer shape matching the inner edge shape of an opening 10 xof the container body 10 so as to fit into the opening 10 x. The framepart 20 c is formed inside the side end which is of the cap part 20 andabuts the upper end surface of the container body 10. In other words,the cap part 20 is configured to have a larger thickness in the areawith the frame part 20 c than in the other area of the cap part 20. Inaddition, the cap part 20 other than the protrusion part 21 has thelargest thickness in the area with the frame part 20 c, the secondlargest thickness in the area outside the frame part 20 c, and thesmallest thickness in the area inside the frame part 20 c.

In addition, each of the structural members of the cap part 20 has across section having an approximately even thickness. The cap part 20has a recess part 21 x corresponding to the protrusion part 21, at theback side of the protrusion part 21. In other words, the protrusion part21 of the cap part 20 is formed, for example, by pressing plate-shapedmember having an even thickness to form a protrusion and a recesstherein. In other words, the container 30 includes the cap part 20having the protrusion part 21 and also having the recess part 21 xformed at the position which is in the inner surface of the wall of thecontainer 30 and corresponds to the position of the protrusion part 21when the protrusion part 21 is formed. The recess part 21 x includes abottom surface 21 y which is the lowermost surface, and a side surface21 z as an inner side surface continuously formed between the bottomsurface 21 y and the inner surface of the wall of the container 30.Accordingly, the cap part 20 includes a side wall part 21 d which formsa side surface 21 c as the outer side surface of the protrusion part 21and a side surface 21 z of the recess part 21 x. As shown in FIG. 2 andFIG. 3, in a plan view, the side wall part 21 d is formed (i) to becontinuous from the outer edge of the rectangular-shaped plate part 21 bto the cap body 20 a along the lateral direction (X-axis direction) ofthe cap part 20 and the longitudinal direction (Y-axis direction), andalong a direction crossing the cap body 20 a. The side wall part 21 dhas four side portions 21 d 1, 21 d 2, 21 d 3, and 21 d 4 facing fourdirections. Adjacent ones of the four side portions 21 d 1, 21 d 2, 21 d3, and 21 d 4 are continuous to each other. Among the four side portions21 d 1, 21 d 2, 21 d 3, and 21 d 4, the paired side portions 21 d 1 and21 d 3 continuous to the outer edge in the lateral direction (X-axisdirection) of the plate part 21 b of the protrusion part 21 are formedto be bent perpendicularly with respect to the cap body 20 a and theplate part 21 b (see FIG. 2). In addition, among the four side portions21 d 1, 21 d 2, 21 d 3, and 21 d 4, the paired side parts 21 d 2 and 21d 4 continuous to the outer edge in the longitudinal direction (Y-axisdirection) of the plate part 21 b of the protrusion part 21 are formedby being bent so as to be farther apart from each other at the positionscloser to the cap body 20 a (see FIG. 3). In other words, the first sidewall 21 c 2 and the second side wall 21 c 4 at the inner side in theX-axis direction of the paired side portions 21 d 2 and 21 d 4 in theY-axis direction of the side wall part 21 d are tilted so as to befarther apart from each other at the positions closer to the uppersurface 20 b of the cap part 20. The side surface 21 z of the recesspart 21 x is a surface which faces the paired wall parts 12 b 2 (laterdescribed) of the base part 12 b of the current collector 12 through theside wall parts 13 c (later described) of the internal insulationsealing member 13.

The internal insulation sealing member 13 has a plate part 13 b and aside wall part 13 c as a first wall part, similarly to the protrusionpart 21 formed in the cap part 20. The internal insulation sealingmember 13 has an upper-part shape corresponding to the shape of therecess part 21 x. The plate part 13 b has the shape of a flat plateparallel to the plate part 21 b of the protrusion part 21, and, in aplan view, has the shape of a rectangle with the sides each parallel tothe X-axis direction or Y-axis direction. The plate part 13 b includesthe aforementioned through-hole 13 a formed therein. The side wall part13 c is formed to perpendicularly extend from the outer edge of theplate part 13 b toward the electrode assembly 11 (that is, downward).The side wall part 13 c has four side parts of 13 c 1, 13 c 2, 13 c 3,and 13 c 4 facing four directions. Adjacent ones of the four side parts13 c 1, 13 c 2, 13 c 3, and 13 c 4 are continuous to each other. Theside wall part 13 c is parallel to the inner surface of theaforementioned side wall part 21 d. In other words, among the four sideparts 13 c 1, 13 c 2, 13 c 3, and 13 c 4, the paired side parts 13 c 1and 13 c 3 respectively extending from the paired side parts in theX-axis direction of the plate part 13 b are formed to be perpendicularto the plate part 13 b. Among the four side parts 13 c 1, 13 c 2, 13 c3, and 13 c 4, the paired side parts 13 c 2 and 13 c 4 are formed torespectively extend, with a tilt, from the paired side parts in theY-axis direction of the plate part 13 b, so as to be farther apart fromeach other at positions more distant from the plate part 13 b. As shownin FIG. 3, the inner surfaces of the paired side portions 21 d 2 and 21d 4 facing each other and the outer surfaces of the paired side parts 13c 2 and 13 c 4 are in contact with each other. The paired side portions21 d 2 and 21 d 4 among the side portions of the side wall part 21 d arecontinuous from the outer edge in the longitudinal direction of theplate part 21 b of the protrusion part 21, and the paired side parts 13c 2 and 13 c 4 extend from respectively corresponding two of the sideportions in the Y-axis direction of the plate part 13 b of the internalinsulation sealing member 13.

In other words, the at least part of the side surface 21 z of the recesspart 21 x is in surface contact with the paired parts 13 c 2 and 13 c 4which are at least parts of the side wall part 13 c of the internalinsulation sealing member 13. In addition, the at least part of the sidesurface 21 z is formed to be tilted with respect to the direction inwhich the protrusion part 21 protrudes. Here, the at least part of theside surface 21 z of the recess part 21 x is paired portions 21 z 2 and21 z 4 facing each other in the side surface 21 z, and the pairedportions 21 z 2 and 21 z 4 are tilted so as to be farther apart fromeach other at positions more distant from the bottom surface 21 y. Inaddition, the paired portions 21 z 2 and 21 z 4 facing each other in theside surface 21 z are formed to be tilted symmetrically with respect tothe direction in which the protrusion part 21 protrudes, along thelongitudinal direction of the cap part 20.

Furthermore, the external Insulation sealing member 22 positioned at theupper part of the protrusion part 21 of the cap part has a shapecorresponding to the shape of the protrusion part 21 as in the case ofthe internal insulation sealing member 13. In the external insulationsealing member 22, the lower surface of the plate part 22 b is incontact with the upper surface of the plate part 21 b of the protrusionpart 21, and the side wall part 22 a extending from the outer edge ofthe plate part 22 b and below the bottom part of the plate part 22 b hasa shape matching the shape of the side wall part 21 d which forms theside surface of the protrusion part 21. The side wall part 22 a has fourside parts 22 a 1, 22 a 2, 22 a 3, and 22 a 4 facing four directions.Adjacent ones of the four side parts 22 a 1, 22 a 2, 22 a 3, and 22 a 4are continuous to each other. Among the four side parts 22 a 1, 22 a 2,22 a 3, and 22 a 4, the paired side parts 22 a 1 and 22 a 3 which extenddownward from the paired side parts in the X-axis direction of the platepart 22 b are formed to be perpendicular to the plate part 22 b. Amongthe four side parts 22 a 1, 22 a 2, 22 a 3, and 22 a 4, the paired sideparts 22 a 2 and 22 a 4 which extend downward from the paired side partsin the Y-axis direction of the plate part 22 b are tilted so as to befarther apart from each other at positions closer to the upper surface20 b of the cap part 20 of the container 30. In other words, the sidewall part 22 a of the external insulation sealing member 22 includes: apart 22 a 2 of the side wall part 22 a as the first side wall partdisposed along the part (the first side wall 21 c 2) of a side surfaceof a first protrusion part 21; and a part 22 a 4 of the side wall part22 a as the second side wall part disposed along the part (the secondside wall 21 c 4) of a side surface of a second protrusion part 21 whichis disposed at the side opposite to the first side wall part. Here, thefirst angle θ1 formed by the part 22 a 2 and the part 22 a 4 of the sidewall part 22 a is equal to the second angle θ2 formed by the first sidesurface 21 c 2 and the second side surface 21 c 4. In other words, theinner surface of the part 22 a 2 in the X-axis direction of the sidewall part 22 a and the first side wall 21 c 2 are closely in contactwith each other, and the inner surface of the part 22 a 4 in the X-axisdirection of the side wall part 22 a and the second side wall 21 c 4 areclosely in contact with each other.

In addition, the distance in the Z-axis direction between the lowersurface of the plate part 22 b and the bottom end of the side wall part22 a is less than the distance in the Z-axis direction from the uppersurface 20 b of the cap body 20 a to the upper surface of the plate part21 b of the protrusion part 21. In other words, as shown in FIG. 2 andFIG. 3, in the state where the external Insulation sealing member 22,the cap part 20, the internal insulation sealing member 13, and thecurrent collector 12 are sandwitched by the terminal body 23 a of theelectrode terminal 23 and the riveted end 23 c and thereby beingpressure-bonded to each other, the end surface 22 f of the end part ofthe side wall part 22 a (that is, the lower end of the side wall part 22a) at the side of the upper surface 20 b of the cap part 20 of thecontainer 30 is apart from the upper surface 20 b of the cap part 20 bya predetermined spacing C.

In this way, in the non-aqueous electrolyte secondary battery 1 in thisembodiment, the cap part 20 has a protrusion part 21 and a correspondingrecess part 21 x, and the external insulation sealing member 22 and theinternal insulation sealing member 13 have shapes matching the shapes ofthe protrusion part 21 and the recess part 21 x.

Next, with reference to FIG. 4, FIGS. 5A and 5B, the structure of thecurrent collector 12 is described in detail. FIG. 4 is a perspectiveview looking up the current collector 12. FIG. 5A is a view in theY-axis direction, and FIG. 5B is a view in the X-axis direction.

As shown in the diagrams, the current collector 12 is formed by, forexample, press-bending a single metal plate, and includes a base part 12b including a part having a flat plate shape, and paired arm parts 12 cwhich extend downward from both the ends in the X-axis direction of thebase part 12 b. In addition, the base part 12 b of the current collector12 is connected to the electrode terminal 23 in the recess part 21 x.The arm part 12 c of the current collector 12 extends from the base part12 b toward the side opposite to the protrusion direction of theprotrusion part 21 (that is, below the cap part 20), and is connected tothe electrode assembly 11.

As shown in FIG. 4 and FIG. 5A, the base part 12 b includes a flat-plateshaped plate part 12 b 1 having a through-hole 12 a formed therein, andpaired wall parts 12 b 2 formed by bending at paired sides in the Y-axisdirection of the plate part 12 b 1. The plate part 12 b 1 is directlyconnected to the electrode terminal 23. The plate part 12 b 1 is formedalong the bottom surface 21 y of the recess part 21 x. The paired wallparts 12 b 2 are formed continuously from opposing sides of the platepart 12 b 1 such that the paired wall parts 12 b 2 have inner endsfacing the side surface 21 z of the recess part 21 x. The paired wallparts 12 b 2 included in the base part 12 b are tilted so as to befarther apart from each other at positions more distant from the platepart 12 b 1, facing, at its inner ends, the side surface 21 z which isthe inner surface of the side wall part 21 d of the recess part 21 x inthe cap part 20 shown in FIG. 3. Each of the paired wall parts 12 b 2 iscontinuous to the corresponding one of the paired arm parts 12 c at itsend part in the Y-axis direction of the container 30 (the right side inFIG. 5B). In other words, the respective wall parts 12 b 2 arecontinuous to the arm part 12 c at only portions thereof closer to theprojection part 11 a of the electrode assembly 11. In other words, thearm part 12 c of the current collector 12 is continuous from the pairedwall parts 12 b 2, and extends from the base part 12 b downward andbelow the cap part 20.

Next, each of the paired arm parts 12 c includes an arm body 12 c 1connected to the electrode assembly 11 and a bridge part 12 c 2 whichbridges the arm body 12 c 1 and the wall parts 12 b 2. Each of thepaired arm bodies 12 c 1 is a long flat plate which extends from theplate part 12 b 1 downward in the direction orthogonal to the plate part12 b 1 along the side surface of the projection part 11 a in the X-axisdirection at the positive electrode side of the electrode assembly 11.In short, the paired arm bodies 12 c 1 are parallel to each other. Asshown in FIG. 3, the paired arm bodies 12 c 1 sandwitch the electrodeassembly 11 therebetween. The arm part 12 c of the current collector 12is connected to the electrode assembly 11 at a position in the Y-axisdirection closer to the short side surface 10 a of the container 30 thanto the position of the protrusion part 21 inside the container 30. Inaddition, the bridge part 12 c 2 connects the arm body 12 c 1 and thewall parts 12 b 2 of the base part 12 by being, when viewed in theX-axis direction, curved from the recess part 21 x toward the side ofthe short side surface 10 a of the container 30. In other words, asshown in FIG. 58B, in the Y-axis direction of the container 30, an edgee2 which is of the arm part 12 c of the current collector 12 and at theside of the short side surface 10 a is positioned closer to the shortside surface 10 a than an edge e1 which is of the base part 12 b of thecurrent collector 12 and at the side of the short side surface 10 a.

Here, as shown in FIG. 5B, the end portions of the paired arm bodies 12c 1 are round when seen from a viewpoint in the X-axis direction. Byconfiguring the arm bodies 12 c 1 to have round end portions, it isprevented that the surface of the electrode assembly 11 is damaged whenthe electrode assembly 11 is connected to the current collector 12. Itis to be noted that the arm bodies 12 c 1 may be configured to haverectangular end portions instead of round end portions.

On the other hand, as shown in FIG. 5A, each of the paired bridge parts12 c 2 has the same angle with respect to the plate part 12 b 1 of thebase part 12 b as the angle of the wall part 12 b 2 with respect to theplate part 12 b 1 of the base part 12 b. In other words, the bridgeparts 12 c 2 are paired structural elements of the current collectors 12formed along the lines extending from the paired wall parts 12 b 2. Thepaired wall parts 12 b 2 of the base part 12 b are formed continuouslyfrom the bridge parts 12 c 2, and are bent with respect to the platepart 12 b 1 of the base part 12 b. In addition, the paired wall parts 12b 2 of the base part 12 b face the side surface 21 z of the recess part21 x through the side wall part 13 c of the internal insulation sealingmember 13. The paired bridge parts 12 c 2 are tilted so as to be fartherapart from each other at the positions closer to the bottom part. Inaddition, the wall parts 12 b 2 of the base part 12 b is in surfacecontact with the side wall part 13 c of the internal insulation sealingmember 13. Since the paired wall parts 12 b 2 and the paired bridgeparts 12 c 2 are tilted in this way, each of the plate parts 12 b 1directly in contact with the plate parts 13 b of the internal insulationsealing members 13 has, in the X-axis direction of the upper surface ofthe plate part 12 b 1, a width W1 smaller than the spacing W2 betweenthe paired arm bodies 12 c 1. Since the wall parts 12 b 2 and the bridgeparts 12 c 2 are formed along the extension lines, and the arm parts 12c and the base parts 12 b of the current collector 12 are integrallyformed, it is easy to form the arm parts 12 c and base parts 12 b of thecurrent collectors 12 having sufficient strength and form the paired armparts 12 c precisely.

In addition, as shown in FIG. 2, FIG. 4, and FIG. 5B, the bridge part 12c 2 extends from the wall part 12 b 2 of the base part 12 b in thedirection toward the Y-axis direction end part of the container 30 suchthat the arm body 12 c 1 is positioned at the Y-axis direction end partside of the container 30. In this way, the outer side of the arm body 12c 1 extends to a point outer than an outer end e1 of the plate part 12 b1.

In the non-aqueous electrolyte secondary battery 1 according to thisembodiment, the paired portions 21 z 2 and 21 z 4 and the pairedportions 13 c 2 and 13 c 4 are formed to be tilted with respect to thedirection in which the protrusion part 21 protrudes and to be parallelto each other. The paired portions 21 z 2 and 21 z 4 are formed to faceeach other in the side surface 21 z as the inner side surface of therecess part 21 x formed on the inner surface of the wall of thecontainer 30, and the paired portions 13 c 2 and 13 c 4 are of the sidewall part 13 c of the internal insulation sealing member 13 andrespectively face the paired portions 21 z 2 and 21 z 4. In addition,the paired portions 21 z 2 and 21 z 4 in the side surface 21 z of therecess part 21 x are tilted so as to be farther apart from each other atpositions more distant from the bottom surface 21 y. Furthermore, thepaired portions 21 z 2 and 21 z 4 in the side surface 21 z of the recesspart 21 x are in surface contact with the paired portions 13 c 2 and 13c 4 in the side surface 13 c of the internal insulation sealing member13.

For this reason, even when the recess part 21 x or the internalinsulation sealing member 13 is formed to have an allowable sizedifference, it is possible to easily bring into close contact the pairedportions 21 z 2 and 21 z 4 in the side surface 21 z of the recess part21 x and the paired portions 13 c 2 and 13 c 4 in the side wall part 13c of the internal insulation sealing member 13, and thereby can increasethe air-tightness around the electrode terminal 23.

In particular, the tilted paired parts 13 c 2 and 13 c 4 in the sidewall part 13 c of the internal insulation sealing member 13 and thetilted paired portions 21 z 2 and 21 z 4 in the side surface 21 z of therecess part 21 x are formed along the longitudinal direction of theInternal insulation sealing member 13 which is rectangular in a planview and the recess part 21 x. For this reason, it is possible to securea wide close-contact area between the recess part 21 x and the internalinsulation sealing member 13. In this way, it is possible to achievebonding with a higher air-tightness.

In addition, since the paired parts 13 c 2 and 13 c 4 in the side wallpart 13 c and the paired portions 21 z 2 and 21 z 4 in the side surface21 z are tilted so as to be farther apart from each other at positionsmore distant from the cap part 20, it is possible to produce a space inwhich the wall parts 12 b 2 of the base part 12 b of the currentcollector 12 to be bonded at that part are also tilted in the samedirection. In other words, it is possible to form the paired arm parts12 c for sandwitching the electrode assembly 11 to extend downward fromthe base part 12 b of the current collector 12 with a spacing which issecured in advance in a predetermined direction of the base part 12 b ofthe current collector 12. In this way, it is possible to form the pairedarm parts 12 c of the current collector 12 to have a spacing W2 largerthan a width W1 in the X-axis direction of the base part 12 b. For thisreason, it is possible to secure a large width in the X-axis directionof the electrode assembly 11, and a large space for the electrodeassembly 11 to be housed in the container 30. Thus, as an advantageouseffect, it is possible to increase the housing efficiency with respectto the capacity of the container 30 of the electrode assembly 11.

In the non-aqueous electrolyte secondary battery 1 according to thisembodiment, the container 30 includes a protrusion part 21 formedthereon, and further includes a recess part 21 x formed, when theprotrusion part 21 is formed, at the position which is on an innersurface of the container 30 and corresponds to the position of theprotrusion part 21. The current collector 12 electrically connected tothe electrode terminal 23 inside the container 30 includes a base part12 b connected to the electrode terminal 23 inside the recess part 21 x.

In this way, the base part 12 b at which the current collector 12 isconnected to the electrode terminal 23 is housed in the recess part 21 xformed in the container 30. Thus, it is possible to match the space forparts other than the recess part 21 x in the inner space of thecontainer 30 to the shape of the electrode assembly 11. In this way, itis possible to reduce wasteful space produced when the electrodeassembly 11 is housed inside the container 30 only by adjusting theouter size of the electrode assembly 11 to the size of the inner space.In this way, the shape of the container 30 is adjusted to the shape ofthe electrode assembly 11 without changing the structure of theelectrode assembly 11. Therefore, it is possible to easily increase thehousing efficiency of the electrode assembly 11 with respect to theinner space of the container 30.

In addition, in the non-aqueous electrolyte secondary battery 1according to this embodiment, the recess part 21 x formed in the cappart 20 has side surfaces 21 z in which paired portions 21 z 2 and 21 z4 facing the paired first wall parts 12 b 2 of the base part 12 b of thecurrent collector 12 are tilted so as to be farther apart from eachother at positions more distant from a bottom surface 21 y of the recesspart 21 x, as in the case of the paired first wall parts 12 b 2. Inother words, it is possible to bond the recess part 21 x and the basepart 12 b of the current collector 12 more strongly by configuring therecess part 21 x to have side surfaces 21 z in which the paired portions21 z 2 and 21 z 4 facing the paired first wall parts 12 b 2 of the basepart 12 b are tilted suitably for the tilted paired first wall parts 12b 2 of the base part 12 b of the current collector 12, as in the case ofthe paired first wall parts 12 b 2. In addition, it is possible tosecure a wide space for housing a bonding tool used to bond theelectrode terminal 23 and the base part 12 b of the current collector12. Thus, it is possible to increase the operability in themanufacturing.

In addition, in the non-aqueous electrolyte secondary battery 1according to this embodiment, the bridge parts 12 c 2 which arecontinuous from the base part 12 b of the current collector 12 to thearm parts 12 c are flat plates which are formed (i) integrally with theplate part 12 b 1 and the paired wall parts 12 b 2 and (ii) to have ashape matching the shape of the inner surface of the recess part 21 x.For this reason, it is possible to reduce the distance from the armbodies 12 c 1 to the plate part 12 b 1 as much as possible, and shortenthe current collection path. For this reason, it is possible to reduceinternal loss in the current collector 12. In addition, since it is easyto form the current collector 12 having the flat plate-shaped bridgeparts 12 c 2, it is possible to reduce mechanical stress added onto thecurrent collector 12 itself.

In addition, in the non-aqueous electrolyte secondary battery 1according to this embodiment, the base part 12 b includes the plate part12 b 1 and the paired wall parts 12 b 2 which are bent with respect tothe plate part 12 b 1, and the paired wall parts 12 b 2 are formedcontinuously with the paired bridge parts 12 c 2 of the paired armbodies 12 c. For this reason, it is possible to increase the strength ofthe base part 12 b of the current collector 12, and prevent deformationof the arm parts 12 c.

In addition, in the non-aqueous electrolyte secondary battery 1according to this embodiment, the paired portions 21 z 2 and 21 z 4facing each other in the side surface 21 z of the recess part 21 x aretilted symmetrically with respect to the direction in which theprotrusion part 21 protrudes. In other words, as shown in FIG. 6, whenthe recess part 21 x and the internal insulation sealing member 13 has arectangular outer shape in a plan view, the portions passing through thestraight line PX in the diagram are symmetrical to each other in thelateral direction, and the portions passing through the straight line PYin the diagram are symmetrical to each other in the longitudinaldirection.

In this way, for example, by forming the paired portions 21 z 2 and 21 z4 to have a shape symmetrical to each other, it is possible to easilymatch the recess part 21 x and the internal insulation sealing member 13even if one of the orientation of the recess part 21 and the orientationof the internal insulation sealing member 13 changes by 180 degrees withrespect to the other when the cap part 20 and the internal insulationsealing member 13 are assembled. In other words, it is possible toeasily align the recess part 21 x and the internal insulation sealingmember 13.

In addition, in the non-aqueous electrolyte secondary battery 1according to this embodiment, the paired portions 21 c 2 and 21 c 4 andthe paired portions 22 a 2 and 22 a 4 are formed to be tilted withrespect to the direction in which the protrusion part 21 protrudes andto be parallel to each other. The paired portions 21 a 2 and 21 a 4 areof at least part of the side surface 21 c of the protrusion part 21formed on the outer surface of the container 30, and the paired portions22 a 2 and 22 a 4 are of the side wall part 22 a of the externalinsulation sealing member 22 and respectively face the paired portions21 c 2 and 21 c 4. In addition, the paired portions of the side surface21 c of the protrusion part 21 are tilted so as to be farther apart fromeach other at positions more distant from the plate part 21 b as the topsurface of the protrusion part 21. For this reason, even when each ofthe protrusion part 21 and the external insulation sealing member 22 isformed to have an allowable size difference, it is possible to easilybring into close contact the paired portions 21 c 2 and 21 c 4 in theside surface 21 c of the protrusion part 21 and the paired portions 22 a2 and 22 a 4 in the side wall part 22 a of the external insulationsealing member 22, and thereby can increase the air-tightness around theelectrode terminal 23.

However, the present invention is not limited to the above embodiment.

In the non-aqueous electrolyte secondary battery 1, the side surface 21z of the recess part 21 x is formed such that (i) the paired portions 21z 1 and 21 z 3 along the X-axis direction of the bottom surface 21 y ofthe recess part 21 x are bent vertically with respect to the cap body 20a and that (ii) the paired portions 21 z 2 and 21 z 4 along the Y-axisdirection of the bottom surface 21 y of the recess part 21 x are bent soas to be farther apart from each other at the positions more distantfrom the bottom surface 21 y. However, this is exemplary andnon-limiting. As another example, the paired portions along the X-axisdirection of the bottom surface 21 y may be formed to be bent so as tobe farther apart from each other at positions more distant from thebottom surface 21 y, and the paired portions along the Y-axis directionof the bottom surface 21 y may be formed to be bent vertically withrespect to the bottom surface 21 y.

It is assumed here that the side wall part 13 c of the internalinsulation sealing member 13 is formed to have a shape matching theshape of the side surface 21 z of the recess part 21 x, and, as in theabove case, that the paired portions 13 c 1 and 13 c 3 along the X-axisdirection of the side wall part 13 c are vertical to the plate part 13b, and that the paired portions 13 c 2 and 13 c 4 along the Y-axisdirection are tilted. However, this is exemplary and non-limiting. Inshort, as in the above case, the paired portions along the X-axisdirection of the side wall part 13 c and the paired portions along theY-axis direction of the same have an interchangeable relationship.Accordingly, the side wall part 13 c of the internal insulation sealingmember 13 may be vertical in the Y-axis direction and may be tilted inthe X-axis direction.

In addition, the side surface 21 z of the recess part 21 x and the sidewall part 13 c of the internal insulation sealing member 13 may betilted in both the Y-axis direction and the X-axis direction.Furthermore, only at least one of the side portions of each of the sidewall part 21 d and the side wall part 13 c may be tilted.

As shown in FIG. 5A, it is assumed here that, in the non-aqueouselectrolyte secondary battery 1 according to this embodiment, the bridgeparts 12 c 2 of the arm parts 12 c of the current collector 12 whenviewed in the Y-axis direction are continuous from the paired wall parts12 b 2 and the paired arm bodies 12 c 1 and have a bent along the innershape of the recess part 21 x. However, the bridge parts 12 c 2 do notalways need to be continuous and have a bent in such a manner. Forexample, as shown in FIG. 7, the bridge parts 32 c 2 of the arm parts 32c of the current collector 32 may have a curve along the paired wallpart 32 b 2 of the base part 32 b and the paired arm bodies 32 c 1. Inthis case, the bridge parts 32 c 2 when viewed in the Y-axis directionare approximated more closely to the outer shape of the electrodeassembly 11 when viewed in the Y-axis direction. Thus, it is possible tofurther increase the housing efficiency. In addition, since it ispossible to form the bridge parts 12 c 2 to have curved surfaces insteadof flat surfaces, it is possible to provide the bridge parts 12 c 2having a rigidity larger than a rigidity obtainable when forming thebridge parts 12 c 2 to have a shape with a bent at the boundariesbetween the paired wall parts 12 b 2 and the paired arm bodies 12 c 1when viewed in the Y-axis direction of the current collector 12. It isto be noted that the structural elements assigned with numericalreferences starting with 32 of the current collector 32 shown in FIG. 7are not described here because the descriptions provided for thestructural elements assigned with numerical references starting with 12can be substituted.

In the non-aqueous electrolyte secondary battery 1 in this embodiment,the recess part 21 x of the cap part 20 is a recess formed to have ashape inverse to the shape of the protrusion part 21 formed on the uppersurface 20 b of the cap part 20. However, the recess part 21 x in thepresent invention may be formed irrespective of the presence or absenceof the protrusion part 21. More specifically, the upper surface may be aflat surface without any protrusion part, and a cap part may be employedwhich has a recess part 21 x formed by performing a process such aspressing or cutting onto the back surface opposite to the upper surface.Even with the configuration, it is possible to increase the housingefficiency of the electrode assembly 11. In addition, since the partother than the recess part 21 x of the cap part 20 has a largerthickness, it is possible to increase the rigidity of the cap part 20and to increase the strength of the non-aqueous electrolyte secondarybattery.

However, it is preferable to form the protrusion part 21 when formingthe recess part 21 x because the following advantageous effects can beobtained. Disposing the electrode terminal 23 on the upper surface ofthe protrusion part 21 used as the protrusion part according to thepresent invention facilitates positioning of the electrode terminal 23,which makes it possible to increase the productivity.

In addition, the electrode assembly in the present invention is awinding-type electrode assembly in the above description, but may be astacking-type electrode assembly.

In addition, the energy storage element is the non-aqueous electrolytesecondary battery 1 represented by the lithium ion secondary battery inthe above description, but may be any other secondary battery such as anickel hydrogen battery which can charge and release electric energy aselectrochemical reactions. Alternatively, the energy storage element maybe a primary battery. Furthermore, the energy storage element may be anelement for directly storing electricity as charge, such as an electricdouble-layer capacitor. In short, the energy storage element in thepresent invention may be any element for storing electricity, and thusthe present invention is not limited to the energy storage elements ofspecific types.

In addition, in the above description, the battery container includingthe container body 10 and the cap part 20 corresponds to an elementcontainer in the present invention, and the electric terminals areprovided on the cap part 20. However, the present invention may beimplemented as an energy storage element having electric terminals atthe side of a container body. In short, the present invention can beimplemented as an energy storage element arbitrarily configured, as longas the energy storage element includes a base part of the currentcollector disposed inside a recess part formed at an arbitrary positioninside the element container. Accordingly, the present invention is notlimited to the states of the connection between the cap part andcontainer body of the element container, and the kinds, shapes, numberof the members of the element container.

In addition, the battery body is made of aluminum, but may contain analuminum alloy, any other metal such as a stainless steel, or a metalcompound. In addition, the battery has a hexahedral shape in appearance,but may have a cylindrical shape instead. In short, the elementcontainer according to the present invention is not limited to elementcontainers having specific configurations in terms of shapes, materials,and so on.

To sum up, the present invention may be implemented by adding variouskinds of modifications to the above embodiment, in addition to theaforementioned variations, within the scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention as described above provides an advantageous effectof allowing a large tolerance and thereby making it easier tomanufacture energy storage elements and thus is applicable to energystorage elements such as secondary batteries.

The invention claimed is:
 1. An energy storage element, comprising: acontainer that includes a container body including an opening and a cappart formed on the opening; an electrode assembly housed in thecontainer; an electrode terminal; and a current collector whichelectrically connects the electrode terminal and the electrode assembly,wherein the cap part of the container comprises: an outer surfaceincluding a protrusion part formed to protrude outward from the outersurface; and an inner surface comprising a recess part formed at aposition corresponding to a position of the protrusion part, the recesspart comprising: a bottom surface which is outermost; and an inner sidesurface formed continuously between the bottom surface and the innersurface of the cap part, at least part of the inner side surface of therecess part being formed to be tilted with respect to a direction inwhich the protrusion part protrudes.
 2. The energy storage elementaccording to claim 1, wherein the electrode terminal comprises aterminal body disposed outside the protrusion part.
 3. The energystorage element according to claim 2, wherein the terminal body isconfigured such that a bus bar is welded thereon.
 4. The energy storageelement according to claim 2, wherein the terminal body is configuredsuch that a terminal of an external load is welded thereon.
 5. Theenergy storage element according to claim 2, wherein the terminal bodyincludes a plate-shaped terminal body.
 6. The energy storage elementaccording to claim 1, further comprising an external insulation sealingmember which insulates the electrode terminal from the cap part.